Magnetic tape revolutionized sound recording and reproduction and broadcasting. It allowed radio, which had always been broadcast live, to be recorded for later or repeated airing. It allowed gramophone records to be recorded in multiple parts, which were then mixed and edited with tolerable loss in quality. It was a key technology in early computer development, allowing unparalleled amounts of data to be mechanically created, stored for long periods, and rapidly accessed.

In recent decades, other technologies have been developed that can perform the functions of magnetic tape. In many cases, these technologies have replaced tape. Despite this, innovation in the technology continues, and Sony and IBM continue to produce new magnetic tape drives.[1]

Over time, magnetic tape made in the 1970s and 1980s can suffer from a type of deterioration called sticky-shed syndrome. It is caused by hydrolysis of the binder in the tape and can render the tape unusable.[2]

Contents

The oxide side of a tape is the surface that can be magnetically manipulated by a tape head. This is the side that stores the information, the opposite side is simply a substrate to give the tape strength and flexibility. The name originates from the fact that the magnetic side of most tapes is typically made of iron oxide, though chromium is used for some tapes. An adhesive binder between the oxide and the substrate holds the two sides together.

Magnetic tape was invented for recording sound by Fritz Pfleumer in 1928 in Germany, based on the invention of magnetic wire recording by Oberlin Smith in 1888 and Valdemar Poulsen in 1898. Pfleumer's invention used a ferric oxide (Fe2O3) powder coating on a long strip of paper. This invention was further developed by the German electronics company AEG, which manufactured the recording machines and BASF, which manufactured the tape. In 1933, working for AEG, Eduard Schuller developed the ring-shaped tape head. Previous head designs were needle-shaped and tended to shred the tape. Another important discovery made in this period was the technique of AC biasing, which improved the fidelity of the recorded audio signal by increasing the effective linearity of the recording medium.

Due to the escalating political tensions, and the outbreak of World War II, these developments in Germany were largely kept secret. Although the Allies knew from their monitoring of Nazi radio broadcasts that the Germans had some new form of recording technology, the nature was not discovered until the Allies acquired captured German recording equipment as they invaded Europe at the end of the war. It was only after the war that Americans, particularly Jack Mullin, John Herbert Orr, and Richard H. Ranger, were able to bring this technology out of Germany and develop it into commercially viable formats.

The practice of recording and editing audio using magnetic tape rapidly established itself as an obvious improvement over previous methods. Many saw the potential of making the same improvements in recording television. Television ("video") signals are similar to audio signals. A major difference is that video signals use more bandwidth than audio signals. Existing audio tape recorders could not practically capture a video signal. Many set to work on resolving this problem. Jack Mullin (working for Bing Crosby) and the BBC both created crude working systems that involved moving the tape across a fixed tape head at very fast speeds. Neither system saw much use. It was the team at Ampex, led by Charles Ginsburg, that made the breakthrough of using a spinning recording head and normal tape speeds to achieve a very high head-to-tape speed that could record and reproduce the high bandwidth signals of video. The Ampex system was called Quadruplex and used 2-inch-wide (51 mm) tape, mounted on reels like audio tape, which wrote the signal in what is now called transverse scan.

A VHS helical scan head drum. Helical and transverse scans made possible to increase the data bandwidth to the necessary point for recording video on tapes, and not just audio.

Later improvements by other companies, particularly Sony, led to the development of helical scan and the enclosure of the tape reels in an easy-to-handle videocassette cartridge. Nearly all modern videotape systems use helical scan and cartridges. Videocassette recorders used to be common in homes and television production facilities, but many functions of the VCR have been replaced with more modern technology. Since the advent of digital video and computerized video processing, optical disc media and digital video recorders can now perform the same role as videotape. These devices also offer improvements like random access to any scene in the recording and "live" time shifting and have replaced videotape in many situations.

In all tape formats, a tape drive uses motors to wind the tape from one reel to another, passing over tape heads to read, write or erase as it moves.

Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The recording medium was a thin strip of one half inch (12.65 mm) wide metal, consisting of nickel-plated bronze (called Vicalloy). Recording density was 128 characters per inch (198 micrometre/character) on eight tracks.

Early IBM 7 track tape drives were floor-standing and used vacuum columns to physically buffer long U-shaped loops of tape. The two tape reels visibly fed tape through the columns, intermittently spinning the reels in rapid, unsynchronized bursts, resulting in visually striking action. Stock shots of such vacuum-column tape drives in motion were widely used to represent "the computer" in movies and television.

Most modern magnetic tape systems use reels that are much smaller than the 10.5 inch open reels and are fixed inside a cartridge to protect the tape and facilitate handling. Many late 1970s and early 1980s home computers used Compact Cassettes, encoded with the Kansas City standard, or several other "standards" such as the Tarbell Cassette Interface. Modern cartridge formats include LTO, DLT, and DAT/DDC.

Tape remains a viable alternative to disk in some situations due to its lower cost per bit. This is a large advantage when dealing with large amounts of data. Though the areal density of tape is lower than for disk drives, the available surface area on a tape is far greater. The highest capacity tape media are generally on the same order as the largest available disk drives (about 5 TB in 2011). Tape has historically offered enough advantage in cost over disk storage to make it a viable product, particularly for backup, where media removability is necessary.

Tape has the benefit of a comparatively long duration during which the media can be guaranteed to retain the data stored on the media. Fifteen (15) to thirty (30) years of archival data storage is cited by manufacturers of modern data tape such as Linear Tape-Open media.

In 2014, Sony and IBM announced that they had been able to record 148 gigabits per square inch with magnetic tape media developed using a new vacuum thin-film forming technology able to form extremely fine crystal particles, allowing true tape capacity of 185 TB.[1][4]

^"Magnetic Materials"(PDF). MEMORY OF THE WORLD: Safeguarding the Documentary Heritage. A guide to Standards, Recommended Practices and Reference Literature Related to the Preservation of Documents of All Kinds. UNESCO. 1998. CII.98/WS/4. Retrieved 12 December 2017.

1.
Plastic film
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Plastic film is a thin continuous polymeric material. Thicker plastic material is called a “sheet”. These thin plastic membranes are used to separate areas or volumes, to items, to act as barriers. Plastic films are used in a variety of applications. These include, packaging, plastic bags, labels, building construction, landscaping, electrical fabrication, photographic film, film stock for movies, video tape, almost all plastics can be formed into a thin film. Polypropylene – Polypropylene can be made a cast film, biaxially oriented film, polyester – BoPET is a biaxially oriented polyester film Nylon Polyvinyl chloride – film can be with or without a Plasticizer A variety of bioplastics and biodegradable plastics are available. Cast – Plastics extrusion can cast film which is cooled or quenched then wound up on a roll, extruded film can be stretched, thinned, or oriented in one or two directions. Blown or tubular process forces air into a ring to expand the film. Flat tenter lines stretch the extruded film before annealing, calender rolls can be used to form film from hot polymers Solution deposition is another film forming process. Often additional coating or printing operations are also used, Films can be modified by physical vapor deposition to make metallised films. Films can be subjected to treatment or Plasma processing, films can have release agents applied as needed. Plastic Films, Technology and Packaging Applications, CRC Press 1992 Yam, K. L. Encyclopedia of Packaging Technology, John Wiley & Sons,2009, ISBN 978-0-470-08704-6

2.
Wire recording
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Wire recording or magnetic wire recording was the first early magnetic recording technology, an analog type of audio storage in which a magnetic recording is made on thin steel wire. The first crude magnetic recorder was invented in 1898 by Valdemar Poulsen, the principles and electronics involved are nearly identical. The first wire recorder was invented in 1898 by Danish-American engineer Valdemar Poulsen, Wire recorders for dictation and telephone recording were made almost continuously by various companies through the 1920s and 1930s, but use of this new technology was extremely limited. Dictaphone and Ediphone recorders, which still employed wax cylinders as the medium, were the devices normally used for these applications during this period. The brief heyday of wire recording lasted from approximately 1946 to 1954, the two organizations licensed dozens of manufacturers in the U. S. Japan, and Europe. Examples are Wilcox-Gay, Pierce, Webcor, and Air King, the popularity even encouraged Sears to provide a model, and some authors to prepare specialized manuals. The earliest magnetic tape recorders, not commercially available in the U. S. until 1948, were too expensive, complicated, for any given level of audio quality, the nearly hair-thin wire had the advantage that it was a much more compact storage medium than tape. The Minifon wire recorder was designed for use and its accessories included a microphone disguised as a wristwatch. There were also wire recorders made to data in satellites. Poulsens original telegraphone and other very early recorders placed the two poles of the head on opposite sides of the wire. The wire is thus magnetised transversely to the direction of travel, the development was to place the two poles on the same side of the wire so that the wire was magnetised along its length or longitudinally. Additionally, the poles were shaped into a V so that the head wrapped around the wire to some extent and this increased the magnetising effect and also increased the sensitivity of the head on replay because it collected more of the magnetic flux from the wire. This system was not entirely immune to twisting but the effects were far less marked, the longitudinal method survives into magnetic tape recording to this day. Compared to tape recorders, wire recording devices have a high media speed, standard postwar wire recorders use a nominal speed of 24 inches per second, making a typical one-hour spool of wire 7,200 feet long. Smaller 30- and 15-minute lengths of wire were employed by the majority of recorders made after 1945, some heavy-duty recorders use the larger Armour spools, which can contain enough wire to record continuously for several hours. Because the wire is pulled past the head by the take-up spool, to facilitate handling as the user threaded the wire across the recording head and affixed it to the take-up spool, some manufacturers attached a strip of plastic to each end of the wire. This was designed to press-fit snugly into either spool, on some machines, moving wire guides perform this function, like the mechanism that distributes line across a fishing reel. After recording or playback, the wire has to be rewound before any further use can be made of the machine, unlike with reel-to-reel tape recorders, the take-up reel on most wire recorders is not removable

3.
Tape recorder
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In its present-day form, it records a fluctuating signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal. Tape-recording devices include reel-to-reel tape deck and the cassette deck, the use of magnetic tape for sound recording originated around 1930. Magnetizable tape revolutionized both the radio broadcast and music recording industries and it gave artists and producers the power to record and re-record audio with minimal loss in quality as well as edit and rearrange recordings with ease. The alternative recording technologies of the era, transcription discs and wire recorders, since some early refinements improved the fidelity of the reproduced sound, magnetic tape has been the highest quality analog sound recording medium available. As of the first decade of the 21st century, analog magnetic tape has been replaced by digital recording technologies for consumer purposes. Some individuals and organizations developed innovative uses for magnetic wire recorders while others investigated variations of the technology, one particularly important variation was the application of an oxide powder to a long strip of paper. This German invention was the start of a string of innovations that have led to present day magnetic tape recordings. The earliest known audio tape recorder was a non-magnetic, non-electric version invented by Alexander Graham Bells Volta Laboratory and patented in 1886. It employed a 3⁄16-inch-wide strip of wax-covered paper that was coated by dipping it in a solution of beeswax and paraffin and then had one side scraped clean, the machine was of sturdy wood and metal construction, and hand-powered by means of a knob fastened to the flywheel. The tape was taken up on the other reel. The sharp recording stylus, actuated by a vibrating mica diaphragm, in playback mode, a dull, loosely mounted stylus, attached to a rubber diaphragm, carried the reproduced sounds through an ear tube to its listener. Both recording and playback heads, mounted alternately on the two posts, could be adjusted vertically so that several recordings could be cut on the same 3⁄16-inch-wide strip. While the machine was never developed commercially, it was an ancestor to the modern magnetic tape recorder which it resembled somewhat in design. The tapes and machine created by Bells associates, examined at one of the Smithsonian Institutions museums, became brittle, the machines playback head was also missing. Otherwise, with some reconditioning, they could be placed into working condition, during the recording process, the tape moved through a pair of electrodes which immediately imprinted the modulated sound signals as visible black stripes into the paper tapes surface. On 13 August 1931, Duston filed USPTO Patent Application #556,743 for Method Of And Apparatus For Electrically Recording And Reproducing Sound And Other Vibrations, and which was renewed in 1934. Magnetic recording was conceived as early as 1877 by the American engineer Oberlin Smith, Analog magnetic wire recording, and its successor, magnetic tape recording, involve the use of a magnetizable medium which moves with a constant speed past a recording head. An electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal

4.
Video tape recorder
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A video tape recorder is a tape recorder designed to record video material on magnetic tape. The first practical tape recorder, using transverse tape head scanning, was developed by Ampex Corporation in 1956. The early VTRs were reel to reel devices which recorded on reels of 2 inch wide magnetic tape. They were used in studios, serving as a replacement for motion picture film stock. Beginning in 1963, videotape machines made instant replay during televised sporting events possible, improved formats, in which the tape was contained inside a videocassette, were introduced around 1969, the machines which play them are called videocassette recorders. The first efforts at recording, using recorders similar to audio recorders with fixed heads, were unsuccessful. The problem was that a signal has a much wider bandwidth than an audio signal. One of the first efforts was the Vision Electronic Recording Apparatus and this machine used a thin steel tape on a 21-inch reel traveling at over 200 inches per second. Despite 10 years of research and improvements, it was never used due to the immense length of tape required for each minute of recorded video. Many other fixed-head recording systems were tried but all required impractically high tape speed and it became clear that practical video recording technology depended on finding some way of recording the wide-bandwidth video signal without the high tape speed required by linear-scan machines. The Ampex VRX-1000 became the worlds first commercially successful videotape recorder in 1956 and it used the 2 Quadruplex format, using two-inch tape. Because of its US$50,000 price, the Ampex VRX-1000 could be afforded only by the television networks and the largest individual stations. In 1963, Philips introduced its EL34001 helical scan recorder and Sony marketed the 2 PV-100, its first reel-to-reel VTR intended for business, medical, airline and educational use. The Telcan, produced by the Nottingham Electronic Valve Company and demonstrated on June 24,1963, was the first home video recorder and it could be bought as a unit or in kit form for £60. However, there were drawbacks, it was expensive, not easy to put together. The Sony model CV-2000, first marketed in 1965, was its first VTR intended for use and was based on half-inch tape. Ampex and RCA followed in 1965 with its own reel-to-reel monochrome VTRs priced under US $1,000 for the consumer market. Prerecorded movies for home replay became available in 1967, the EIAJ format was a standard half-inch format used by various manufacturers

5.
Sound recording and reproduction
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Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording, prior to the development of analog recording, there were mechanical systems for reproducing instrumental music, such as wind-up music boxes and later, in the late 19th century, player pianos. Analog sound reproduction is the process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves. Digital recording and reproduction converts the sound signal picked up by the microphone to a digital form by the process of digitization. This lets the audio data be stored and transmitted by a variety of media. Whereas successive copies of an analog recording tend to degrade in quality, as noise is added. A digital audio signal must be reconverted to analog form during playback before it is amplified and connected to a loudspeaker to produce sound, long before sound was first recorded on cylinders or records, music was recorded—first by written music notation, then also by mechanical devices. Fowler, this. cylinder with raised pins on the surface remained the device to produce and reproduce music mechanically until the second half of the nineteenth century. The Banu Musa brothers also invented an automatic flute player, which appears to have been the first programmable machine, according to Fowler, the automata were a robot band that performed. more than fifty facial and body actions during each musical selection. In the 14th century, Flanders introduced a mechanical bell-ringer controlled by a rotating cylinder, similar designs appeared in barrel organs, musical clocks, barrel pianos, and musical boxes. A music box is a musical instrument that produces sounds by the use of a set of pins placed on a revolving cylinder or disc so as to pluck the tuned teeth of a steel comb. They were developed from musical snuff boxes of the 18th century, some of the more complex boxes also have a tiny drum and/or bells, in addition to the metal comb. The fairground organ, developed in 1892, used a system of accordion-folded punched cardboard books, the player piano, first demonstrated in 1876, used a punched paper scroll that could store an long piece of music. The most sophisticated of the rolls were hand-played, meaning that the roll represented the actual performance of an individual. This technology to record a live performance onto a piano roll was not developed until 1904, piano rolls were in continuous mass production from 1896 to 2008. A1908 U. S. Supreme Court copyright case noted that, in 1902 alone, the use of piano rolls began to decline in the 1920s although one type is still being made today. The first device that could record actual sounds as they passed through the air was the phonautograph, the earliest known recordings of the human voice are phonautograph recordings, called phonautograms, made in 1857. They consist of sheets of paper with sound-wave-modulated white lines created by a stylus that cut through a coating of soot as the paper was passed under it

6.
Broadcasting
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Broadcasting began with AM radio, which came into popular use around 1920 with the spread of vacuum tube radio transmitters and receivers. Before this, all forms of communication were one-to-one, with the message intended for a single recipient. Over the air broadcasting is usually associated with radio and television, the receiving parties may include the general public or a relatively small subset, the point is that anyone with the appropriate receiving technology and equipment can receive the signal. The field of broadcasting includes both government-managed services such as radio, community radio and public television, and private commercial radio. The U. S. Code of Federal Regulations, title 47, part 97 defines broadcasting as transmissions intended for reception by the general public, private or two-way telecommunications transmissions do not qualify under this definition. For example, amateur and citizens band radio operators are not allowed to broadcast, as defined, transmitting and broadcasting are not the same. Transmissions using a wire or cable, like television, are also considered broadcasts. In the 2000s, transmissions of television and radio programs via streaming digital technology have increasingly been referred to as broadcasting as well, the earliest broadcasting consisted of sending telegraph signals over the airwaves, using Morse code, a system developed in the 1830s by Samuel F. B. Morse, physicist Joseph Henry and Alfred Vail and they developed an electrical telegraph system which sent pulses of electric current along wires which controlled an electromagnet that was located at the receiving end of the telegraph system. A code was needed to transmit natural language using only these pulses, Morse therefore developed the forerunner to modern International Morse code. Audio broadcasting began experimentally in the first decade of the 20th century, by the early 1920s radio broadcasting became a household medium, at first on the AM band and later on FM. Television broadcasting started experimentally in the 1920s and became widespread after World War II, satellite broadcasting was initiated in the 1960s and moved into general industry usage in the 1970s, with DBS emerging in the 1980s. Originally all broadcasting was composed of signals using analog transmission techniques but in the 2000s. In general usage, broadcasting most frequently refers to the transmission of information, Analog audio vs. HD Radio Analog television vs.9 zettabytes. This is the equivalent of 55 newspapers per person per day in 1986. Historically, there have been several methods used for broadcasting electronic media audio and/or video to the public, Telephone broadcasting. Telephone broadcasting also grew to include telephone services for news and entertainment programming which were introduced in the 1890s. These telephone-based subscription services were the first examples of electrical/electronic broadcasting, Radio broadcasting, audio signals sent through the air as radio waves from a transmitter, picked up by an antenna and sent to a receiver

7.
Radio
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When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form, Radio systems need a transmitter to modulate some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation. Radio systems also need an antenna to convert electric currents into radio waves, an antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual stations to be selected, the electromagnetic wave is intercepted by a tuned receiving antenna. Radio frequencies occupy the range from a 3 kHz to 300 GHz, a radio communication system sends signals by radio. The term radio is derived from the Latin word radius, meaning spoke of a wheel, beam of light, however, this invention would not be widely adopted. The switch to radio in place of wireless took place slowly and unevenly in the English-speaking world, the United States Navy would also play a role. Although its translation of the 1906 Berlin Convention used the terms wireless telegraph and wireless telegram, the term started to become preferred by the general public in the 1920s with the introduction of broadcasting. Radio systems used for communication have the following elements, with more than 100 years of development, each process is implemented by a wide range of methods, specialised for different communications purposes. Each system contains a transmitter, This consists of a source of electrical energy, the transmitter contains a system to modulate some property of the energy produced to impress a signal on it. This modulation might be as simple as turning the energy on and off, or altering more subtle such as amplitude, frequency, phase. Amplitude modulation of a carrier wave works by varying the strength of the signal in proportion to the information being sent. For example, changes in the strength can be used to reflect the sounds to be reproduced by a speaker. It was the used for the first audio radio transmissions. Frequency modulation varies the frequency of the carrier, the instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal. FM has the capture effect whereby a receiver only receives the strongest signal, Digital data can be sent by shifting the carriers frequency among a set of discrete values, a technique known as frequency-shift keying. FM is commonly used at Very high frequency radio frequencies for high-fidelity broadcasts of music, analog TV sound is also broadcast using FM. Angle modulation alters the phase of the carrier wave to transmit a signal

8.
Sony
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Sony Corporation is a Japanese multinational conglomerate corporation that is headquartered in Kōnan, Minato, Tokyo. Its diversified business includes consumer and professional electronics, gaming, entertainment, the company is one of the leading manufacturers of electronic products for the consumer and professional markets. Sony was ranked 116th on the 2015 list of Fortune Global 500 and these make Sony one of the most comprehensive entertainment companies in the world. The group consists of Sony Corporation, Sony Pictures Entertainment, Sony Interactive Entertainment, Sony Music Entertainment, Sony Financial Holdings and others. Sony is among the Semiconductor sales leaders by year and as of 2013, the companys current slogan is BE MOVED. Their former slogans were make. believe, like. no. other, Sony has a weak tie to the SMFG keiretsu, the successor to the Mitsui keiretsu. Sony began in the wake of World War II, in 1946, Masaru Ibuka started an electronics shop in a department store building in Tokyo. The company had $530 in capital and a total of eight employees, in the following year he was joined by his colleague, Akio Morita, and they founded a company called Tokyo Tsushin Kogyo 東京通信工業. The company built Japans first tape recorder, called the Type-G, in 1958 the company changed its name to Sony. When Tokyo Tsushin Kogyo was looking for a name to use to market themselves, they strongly considered using their initials. The primary reason they did not is that the railway company Tokyo Kyuko was known as TTK, the company occasionally used the acronym Totsuko in Japan, but during his visit to the United States, Morita discovered that Americans had trouble pronouncing that name. Another early name that was tried out for a while was Tokyo Teletech until Akio Morita discovered that there was an American company already using Teletech as a brand name, the name Sony was chosen for the brand as a mix of two words. One was the Latin word sonus, which is the root of sonic and sound, and the other was sonny, a common slang term used in 1950s America to call a boy. In the 1950s Japan sonny boys, was a word into Japanese which connoted smart and presentable young men. The first Sony-branded product, the TR-55 transistor radio, appeared in 1955, at the time of the change, it was extremely unusual for a Japanese company to use Roman letters to spell its name instead of writing it in kanji. The move was not without opposition, TTKs principal bank at the time and they pushed for a name such as Sony Electronic Industries, or Sony Teletech. Akio Morita was firm, however, as he did not want the company tied to any particular industry. Eventually, both Ibuka and Mitsui Banks chairman gave their approval, according to Schiffer, Sonys TR-63 radio cracked open the U. S. market and launched the new industry of consumer microelectronics

9.
IBM
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International Business Machines Corporation is an American multinational technology company headquartered in Armonk, New York, United States, with operations in over 170 countries. The company originated in 1911 as the Computing-Tabulating-Recording Company and was renamed International Business Machines in 1924, IBM manufactures and markets computer hardware, middleware and software, and offers hosting and consulting services in areas ranging from mainframe computers to nanotechnology. IBM is also a research organization, holding the record for most patents generated by a business for 24 consecutive years. IBM has continually shifted its business mix by exiting commoditizing markets and focusing on higher-value, also in 2014, IBM announced that it would go fabless, continuing to design semiconductors, but offloading manufacturing to GlobalFoundries. Nicknamed Big Blue, IBM is one of 30 companies included in the Dow Jones Industrial Average and one of the worlds largest employers, with nearly 380,000 employees. Known as IBMers, IBM employees have been awarded five Nobel Prizes, six Turing Awards, ten National Medals of Technology, in the 1880s, technologies emerged that would ultimately form the core of what would become International Business Machines. On June 16,1911, their four companies were amalgamated in New York State by Charles Ranlett Flint forming a fifth company, the Computing-Tabulating-Recording Company based in Endicott, New York. The five companies had 1,300 employees and offices and plants in Endicott and Binghamton, New York, Dayton, Ohio, Detroit, Michigan, Washington, D. C. and Toronto. They manufactured machinery for sale and lease, ranging from commercial scales and industrial time recorders, meat and cheese slicers, to tabulators and punched cards. Thomas J. Watson, Sr. fired from the National Cash Register Company by John Henry Patterson, called on Flint and, Watson joined CTR as General Manager then,11 months later, was made President when court cases relating to his time at NCR were resolved. Having learned Pattersons pioneering business practices, Watson proceeded to put the stamp of NCR onto CTRs companies and his favorite slogan, THINK, became a mantra for each companys employees. During Watsons first four years, revenues more than doubled to $9 million, Watson had never liked the clumsy hyphenated title of the CTR and in 1924 chose to replace it with the more expansive title International Business Machines. By 1933 most of the subsidiaries had been merged into one company, in 1937, IBMs tabulating equipment enabled organizations to process unprecedented amounts of data, its clients including the U. S. During the Second World War the company produced small arms for the American war effort, in 1949, Thomas Watson, Sr. created IBM World Trade Corporation, a subsidiary of IBM focused on foreign operations. In 1952, he stepped down after almost 40 years at the company helm, in 1957, the FORTRAN scientific programming language was developed. In 1961, IBM developed the SABRE reservation system for American Airlines, in 1963, IBM employees and computers helped NASA track the orbital flight of the Mercury astronauts. A year later it moved its headquarters from New York City to Armonk. The latter half of the 1960s saw IBM continue its support of space exploration, on April 7,1964, IBM announced the first computer system family, the IBM System/360

10.
Tape head
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A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. They can also be used to read credit/debit/gift cards because the strip of tape on the back of a credit card stores data the same way that other magnetic tapes do. Cassettes, reel-to-reel tapes, 8-tracks, VHS tapes, and even floppy disks and modern hard drive disks all use the principle of physics to store. The medium is magnetized in a pattern and it then moves at a constant speed over an electromagnet. Since the moving tape is carrying a changing magnetic field with it, it induces a voltage across the head. That voltage can then be amplified and connected to speakers in the case of audio, or measured and sorted into 1s, a head consists of a core of magnetic material arranged into a doughnut shape or toroid, into which a very narrow gap has been let. This gap is filled with a material, such as gold. This forces the magnetic flux out of the gap into the tape medium more than air would. The flux thus magnetises the tape at that point, while a head is reversible in principle, and very often in practice, there are desirable characteristics that differ between the playback and recording phases. One of these is the impedance of the coil - playback preferring a high impedance, in the very best tape recorders, separate heads are used to avoid compromising these desirable characteristics. Having separate heads for recording and playback has other advantages, such as off-tape monitoring during recording, the width of the head gap is also critical - the narrower the gap, the better the head will be - a narrow gap gives much better transcription in the magnetic domain. In this way, gaps of the order of micrometres are achievable, a record head, on the other hand, has a gap typically six times larger than that of the replay head, this gives a larger flux to magnetise the tape. The larger gap does not affect frequency response because the image is made by the trailing edge of the gap. A combined record/replay head has a compromise size gap typically three times that of a replay only head, there are also negative aspects of narrow head gaps, particularly for magnetic recording. The narrower the gap, the more bias signal must be used to maintain linearity of the signal on tape. This reduces high frequency headroom, particularly at lower tape speeds, manufacturers must find a compromise between intended tape speeds and head gaps for this reason. The physical design of a head depends on whether it is fixed or rotating, in either case, the face of the head where the gap is must be made hard wearing and highly smooth to avoid excessive head wear. It can also be seen due to the construction method of the head gap, head wear will tend to widen the gap

11.
Chromium
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Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin, sugar and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature. Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, protective, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, Chromium, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm. Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist

12.
Compact Cassette
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The Compact Cassette or Musicassette, also commonly called cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. It was released by Philips in 1962, having developed in Hasselt. Compact cassettes come in two forms, either already containing content as a cassette, or as a fully recordable blank cassette. Its uses ranged from portable audio to home recording to data storage for early microcomputers, the first cassette player designed for use in car dashes was introduced in 1968. Between the early 1970s and the early 2000s, the cassette was one of the two most common formats for prerecorded music, first alongside the LP record and later the compact disc. Compact Cassettes contain two miniature spools, between which a magnetically coated, polyester-type plastic film is passed and wound and these spools and their attendant parts are held inside a protective plastic shell. This reversal is achieved either by flipping the cassette, or by having the machine itself change the direction of tape movement. In 1935, decades before the introduction of the Compact Cassette, AEG released the first reel-to-reel tape recorder and it was based on the invention of the magnetic tape by Fritz Pfleumer, which used similar technology but with open reels. These instruments were expensive and relatively difficult to use and were therefore used mostly by professionals in radio stations. In 1958, following four years of development, RCA Victor introduced the stereo, quarter-inch, reversible, however, it was a large cassette, and offered few pre-recorded tapes. Despite the multiple versions, it failed, consumer use of tape only took off in the early 1960s, after playback machines reached a comfortable, user-friendly design. This was achieved primarily by the introduction of transistors which replaced the bulky, fragile, reel-to-reel tape then became more suitable to household use, but still remained an esoteric product. The team at Philips was led by Lou Ottens in Hasselt, Philips was competing with Telefunken and Grundig in a race to establish its cassette tape as the worldwide standard, and it wanted support from Japanese electronics manufacturers. However, the Philips Compact Cassette became dominant as a result of Philips decision to license the format free of charge, Philips also released the Norelco Carry-Corder 150 recorder/player in the US in November 1964. By 1966 over 250,000 recorders had been sold in the US alone, by 1968,85 manufacturers had sold over 2.4 million players. By the end of the 1960s, the business was worth an estimated 150 million dollars. In the early years sound quality was mediocre, but it improved dramatically by the early 1970s when it caught up with the quality of 8-track tape, the Compact Cassette went on to become a popular alternative to the 12-inch vinyl LP during the late 1970s. The mass production of blank Compact Cassettes began in 1964 in Hanover, prerecorded music cassettes were launched in Europe in late 1965